Since a gas generator is installed on a vehicle, it is desirable that the weight of the gas generator be as small as possible. For this purpose, some of the components constituting the gas generator are known to be formed of a resin. In particular, in a pyrotechnic gas generator in which a solid gas generating agent is accommodated inside a housing and a combustion gas is generated by combustion thereof, because high-temperature heat is generated by activation, heat resistance should be investigated when a resin is used.
JP-A No. 4-50057 discloses a gas generator using a resin in an outer container 16. In the inner space formed by the outer container made of synthetic resin, that is formed by a diffuser shell 30 and a base shell 32, an inner wall of a space (filter chamber) 52 where filter members 40, 42 are accommodated is provided with a metal coating 54 to prevent the resin from burning by the heat of generated gas.
In JP-A No. 4-50057, the combustion of resin is inhibited by using a heat-resistance material, but no measures are taken with respect to discharge ports 44, 46 where the gas flow velocity is the highest. The discharge ports 44, 46 are portions that discharge the combustion gas, and these portions are affected by high-velocity collisions with high-temperature gas and exposed to conditions more severe than the inner wall of the filter chamber during activation. Therefore, the resin constituting these portions is melted and damaged (referred to hereinbelow as “melting damage”), the opening surface area changes, and the output performance of the inflator itself changes in the course of activation.